Unknown raising standards worldwide™ NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BSI Standards Publication BS EN 15938 2010 BS 2000 586 2010 Automotive fuels — Ethanol blend[.]
Licensed copy: The University of Hong Kong, The University of Hong Kong, Version correct as of 30/10/2010 06:04, (c) BSI BS EN 15938:2010 BS 2000-586:2010 BSI Standards Publication Automotive fuels — Ethanol blending component and ethanol (E85) automotive fuel — Determination of electrical conductivity NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW raising standards worldwide™ Licensed copy: The University of Hong Kong, The University of Hong Kong, Version correct as of 30/10/2010 06:04, (c) BSI BS EN 15938:2010 BRITISH STANDARD National foreword This British Standard is the UK implementation of EN 15938:2010 The UK participation in its preparation was entrusted to Technical Committee PTI/13, Petroleum Testing and Terminology A list of organizations represented on this committee can be obtained on request to its secretary This publication does not purport to include all the necessary provisions of a contract Users are responsible for its correct application © BSI 2010 ISBN 978 580 67064 ICS 75.160.20 Compliance with a British Standard cannot confer immunity from legal obligations This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 October 2010 Amendments issued since publication Date Text affected Licensed copy: The University of Hong Kong, The University of Hong Kong, Version correct as of 30/10/2010 06:04, (c) BSI BS EN 15938:2010 EN 15938 EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM September 2010 ICS 75.160.20 English Version Automotive fuels - Ethanol blending component and ethanol (E85) automotive fuel - Determination of electrical conductivity Carburants pour automobiles - Éthanol comme base de mélange l'essence et carburant éthanol (E85) pour automobiles - Détermination de la conductivité électrique Kraftstoffe für Kraftfahrzeuge - Ethanol als Blendkomponente und Ethanolkraftstoff (E85) Bestimmung der elektrischen Leitfähigkeit This European Standard was approved by CEN on August 2010 CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN Management Centre or to any CEN member This European Standard exists in three official versions (English, French, German) A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the official versions CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels © 2010 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members Ref No EN 15938:2010: E Licensed copy: The University of Hong Kong, The University of Hong Kong, Version correct as of 30/10/2010 06:04, (c) BSI BS EN 15938:2010 EN 15938:2010 (E) Contents Page Foreword 3 1 Scope 4 2 Normative references 4 3 Terms and definitions 4 4 Principle 5 5 Reagents 6 6 Apparatus .6 7 Sampling 6 8 8.1 8.1.1 8.1.2 8.1.3 8.1.4 8.2 8.2.1 8.2.2 8.3 Procedure .7 Preparation of the measuring device 7 General 7 Cleaning of the sample vessel .7 Cleaning of the measuring cell .7 Filling the sample into the sample vessel 7 Calibration 7 Interferences 7 Checking the cell constant 8 Measurement procedure .8 9 Expression of results 8 10 10.1 10.2 10.3 Precision 8 General 8 Repeatability, r .8 Reproducibility, R 9 11 Test report 9 Bibliography 10 Licensed copy: The University of Hong Kong, The University of Hong Kong, Version correct as of 30/10/2010 06:04, (c) BSI BS EN 15938:2010 EN 15938:2010 (E) Foreword This document (EN 15983:2010) has been prepared by Technical Committee CEN/TC 19 “Gaseous and liquid fuels, lubricants and related products of petroleum, synthetic and biological origin”, the secretariat of which is held by NEN This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by March 2011, and conflicting national standards shall be withdrawn at the latest by March 2011 This document was prepared by CEN/TC 19 Ethanol Task Force under responsibility of its Working Group 21 and is based on DIN 51627-4 [1] According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom Licensed copy: The University of Hong Kong, The University of Hong Kong, Version correct as of 30/10/2010 06:04, (c) BSI BS EN 15938:2010 EN 15938:2010 (E) Scope This European Standard specifies a test method for the determination of the electrical conductivity in ethanol and ethanol (E85) automotive fuel in the range from approximately (0,3 to 5) µS/cm at a temperature of 25 °C (see Clause 4) The electrical conductivity is determined from the measured electrical conductance The electrical conductivity is an important analytical criterion for the ascertainment and control of anionic and cationic components in ethanol and ethanol (E85) automotive fuel Some of these components can exhibit corrosive properties Normative references The following referenced documents are indispensable for the application of this document For dated references, only the edition cited applies For undated references, the latest edition of the referenced document (including any amendments) applies EN ISO 3170, Petroleum liquids — Manual sampling (ISO 3170:2004) EN ISO 3171, Petroleum liquids — Automatic pipeline sampling (ISO 3171:1988) Terms and definitions For the purposes of this document, the following terms and definitions apply 3.1 electrical conductance G reciprocal value of the electrical resistance NOTE The electrical conductance is expressed in siemens (S) or Ω–1 3.2 electrical resistance R measurement value of a sample, directly determined by means of the conductivity meter, which increases with the sample length l and decreases with the sample cross-section A NOTE The electrical resistance of a sample is expressed in ohms (Ω) The relation between R and the electrical conductance (3.1) is shown in Equation (1) G= R (1) 3.3 electrical conductivity σT material-dependent measure of the electrical current conducted in an electrical field by the ions present in the solution NOTE The material-dependent electrical conductivity of a solution is related to the electrical current which is achieved by moving ions of the solution in an electrical field It is therefore applicable as a method to limit ionic contamination in alcohols and alcohol based fuels The electrical conductivity σT is determined in accordance with Equation (2) from the determined electrical conductance G (3.1) and the geometrical dimensions of the measuring cell (length and effective cross-section) which are added to form the cell constant K (3.4): Licensed copy: The University of Hong Kong, The University of Hong Kong, Version correct as of 30/10/2010 06:04, (c) BSI BS EN 15938:2010 EN 15938:2010 (E) σT = G ⋅ l =G⋅K A (2) where: σT -1 is the electrical conductivity of the sample, in µS cm -1 -1 (1 S m = 104 µS cm ), at the measurement temperature T, in °C; l is the length of the measured section (geometrical electrode gap), in m or, following the respective unit conversion, in cm, with m = 100 cm; A is the effective cross-section of the measuring cell, in m2 or, following the respective unit conversion, in cm2, with m2 = 10 cm2; K is the cell constant of the measuring cell in m–1 or, following the respective unit conversion, in cm–1, with m–1 = 0,01 cm–1 NOTE The electrical conductivity of a solution depends on the temperature; therefore the temperature is given together with the measurement value Hence, the electrical conductivity, which is mostly determined at 25 °C, is designated as σ25 NOTE The electrical conductivity depends on ion concentration, ion type, temperature and viscosity of the solution Therefore its measurement range can be large "Ultrapure" (deionized and demineralised) water for example, due to its -1 -1 self-dissociation at 25 °C, has an electrical conductivity of 0,054 83 µS cm (5,483 µS m ) 3.4 cell constant K geometrical dimension of the measuring cell used to form one value NOTE The electrical conductivity σ (3.3) cannot be calculated simply from the electrical resistance R (3.2) and the geometrical cell dimensions because its functional relationship to the cell dimensions is very complex, especially in cases where the geometry is not cubical Therefore, the measuring cell is calibrated by means of a calibration solution of known electrical conductivity σ* The cell constant K is determined in accordance with Equation (3) from the measured electrical conductance G* caused by the calibration solution and its known electrical conductivity σ* K = * σ 25 * G 25 (3) where: K is the cell constant of the measuring cell in m–1 or, following the respective unit conversion, in cm–1 (1 m-1 = 0,01 cm–1); * G25 is the measured electrical conductance at 25 °C in the measuring cell filled with the calibration solution, expressed in S; -1 -1 -1 -1 * σ 25 is the electrical conductivity of the calibration solution at 25 °C, in S m or µS cm (1 S m = 104 µS cm ) Principle The determination of the electrical conductivity in ethanol or ethanol fuel is carried out by means of a direct conductometer (6.1) measurement, using a measuring cell (6.2) suitable for a measurement range of -1 approximately (0,01 to 5) µS cm The measurement is carried out at a sample temperature of (25 ± 0,1) °C As electrical conductivity is strongly depending on temperature, selection of another measurement Licensed copy: The University of Hong Kong, The University of Hong Kong, Version correct as of 30/10/2010 06:04, (c) BSI BS EN 15938:2010 EN 15938:2010 (E) temperature and the subsequent conversion of the electrical conductance to a target temperature of 25 °C is not allowed Reagents 5.1 Ethanol, absolute, of analytical grade or a similar quality, for cleaning and rinsing the measuring cell (6.2), the sample vessel (6.4) and all the other vessels/containers with which the sample can come into contact 5.2 -1 Calibration solution, KCl solution having a conductivity σ25 of max.100 µS cm -1 5.3 Water, deionized or distilled with a maximum conductivity of µS cm , for cleaning and rinsing the sample vessel (6.4) and the measuring cell (6.2) Apparatus 6.1 Conductometer, suitable of being operated with measuring cells (6.2) having a cell constant of approximately (0,1 to 1) cm–1, with an alternating voltage of a frequency between 50 Hz and 500 Hz in the measuring cell (6.2), directly displaying the measured conductivity to the nearest 0,01 µS cm-1 at least A single-point calibration using a single KCl calibration solution (5.2) is sufficient 6.2 Measuring cell, manufactured from a material inert to ethanol or ethanol fuel, for example high-grade steel The cell constant should be in the range (0,1 and 1) cm–1, preferably close to 0,1 cm–1 The measuring cell is introduced from above into the sample vessel (6.4), through a cover, and fixed in a way it is completely immersed in the solution to be measured 6.3 Temperature sensor, with an accuracy of ± 0,1 °C or better, suitable for recording the temperature of the solution subjected to measurement at approximately 25 °C This sensor can also be integrated in the measuring cell (6.2) The temperature signal is indicated on a display to the nearest ± 0,1 °C 6.4 Thermostatable glass sample vessel, having a capacity of 20 ml to 500 ml, into which the sample to be measured is filled The sample vessel may be designed as a double-walled glass vessel, for example, which is thermostated by means of a circulating liquid Alternatively, a thermostatable flow-through vessel may be used, provided it is ensured that the substance to be measured can be maintained at a temperature of (25 ± 0,1) °C, the measuring cell (6.2) is completely immersed, and all requirements for cleaning are also complied with 6.5 Thermostat with thermometer, suitable for thermostating the sample vessel (6.4) to (25 ± 0,1) °C 6.6 Stirrer for ensuring a homogeneous temperature in the sample by stirring it with a magnetic stirrer and a polytetrafluorethylene-coated stirring magnet Sampling Unless specified otherwise, samples shall be taken in accordance with EN ISO 3170 or EN ISO 3171 and/or the requirements of national standards regarding the sampling of fuels Licensed copy: The University of Hong Kong, The University of Hong Kong, Version correct as of 30/10/2010 06:04, (c) BSI BS EN 15938:2010 EN 15938:2010 (E) Only glass bottles shall be used for samples The glass bottles shall be cleaned very thoroughly and rinsed at least twice using the product to be sampled prior to the actual sampling Avoid a stopper made up of aluminium, brass, copper, lead, plated steel, zinc, natural rubber, leather, cork, polyurethane, PVC and polyamides For any other handling of the samples particular attention shall be paid to avoid any risk of further contamination Procedure 8.1 Preparation of the measuring device 8.1.1 General The device manufacturer's instructions shall be followed for the preparation and operation of the conductometer (6.1) and the measuring cell (6.2) The thermostat (6.5) is connected with the sample vessel (6.4) and set to achieve a temperature of (25 ± 0,1) °C in the sample vessel 8.1.2 Cleaning of the sample vessel Before the measurement, the sample vessel (6.4) is rinsed several times with ethanol (5.1) The rest of the ethanol used for rinsing shall be dripped off If the sample vessel (6.4) has been used before for saline samples, it shall additionally be cleaned thoroughly with water (5.3) prior to using it for ethanol or ethanol fuel Subsequently, it is dried in the drying oven at 80 °C Afterwards it is rinsed once more using ethanol (5.1) If there are any visible contaminations (e.g stains) on the inner glass surface of the sample vessel (6.4), the vessel shall not be used 8.1.3 Cleaning of the measuring cell The measuring cell (6.2) is also cleaned by rinsing it thoroughly with ethanol (5.1) If the measuring cell (6.2) had been used before for saline samples, it shall be cleaned thoroughly with water (5.3) prior to using it for ethanol or ethanol fuel Subsequently, it is thoroughly rinsed with ethanol (5.1) If there are any visible contaminations (e.g stains) on the inner surface of the measuring cell (6.2), the cell shall not be used 8.1.4 Filling the sample into the sample vessel The sample is filled into the sample vessel (6.4) by pouring it directly from the sample container into the vessel Should an intermediate vessel be required for transferring, this vessel shall first be cleaned thoroughly using water (5.3), and dried in the drying oven at 80 °C Before the intermediate vessel is used, it is rinsed with ethanol (5.1) Subsequently it shall be dripped off Rubbing its inside with a fibrous cloth shall be avoided The size of the intermediate vessel shall be chosen such that it is filled up to at least half its height If there are any visible contaminations (e.g stains) at the surface of the glass on the inside of the vessel, the vessel shall not be used 8.2 8.2.1 Calibration Interferences The measurement values of the electrical conductivity can very strongly be influenced by contaminations in the sample as well as by pollutions of the measuring cell (6.2) (suspended matter, grease or oil) Such interferences cannot easily be detected in routine operation; therefore, the cell constant should regularly be checked by means of a reference solution or the calibration solution (5.2) Licensed copy: The University of Hong Kong, The University of Hong Kong, Version correct as of 30/10/2010 06:04, (c) BSI BS EN 15938:2010 EN 15938:2010 (E) 8.2.2 Checking the cell constant The cell constant is determined at (25 ± 0,1) °C using the calibration solution (5.2), and stored in the device and recorded In order to enable a fast measurement, the calibration solution (5.2) should be pre-adjusted to a temperature of 25 °C NOTE The cell constant is a parameter of the measuring cell The conductometer (6.1) automatically works out this value with calibration solution (5.2) The measuring cell (6.2) and the sample vessel (6.4) are cleaned of any adhering rinsing ethanol (5.1) To so, the sample vessel (6.4) is filled with the calibration solution (5.2) and, after the measuring cell (6.2) has been immersed in the solution, the solution is stirred for at least one minute Subsequently, the sample vessel (6.4) is emptied und refilled with the calibration solution (5.2) The measuring cell (6.2) is immersed in the solution, and the lid is closed In order to achieve a homogeneous temperature distribution, the solution is gently stirred As soon as a constant temperature of (25 ± 0,1) °C has been achieved in the solution, the calibration measurement can be started The determined cell constant is stored in the device in accordance with the manufacturer's instructions and recorded rounded to the nearest 0,001 cm–1 Following the calibration of the conductometer (6.1) the first measurement using the calibration solution (5.2) is carried out The sample vessel (6.4) is emptied and refilled with the calibration solution (5.2) without another intermediate cleaning step The measurement result shall not deviate by more than % relative from the conductivity * σ 25 of the calibration solution (5.2) 8.3 Measurement procedure After cleaning the sample vessel (6.4) and the measuring cell (6.2) in accordance with 8.1.2 and 8.1.3, the sample to be measured is filled into the sample vessel (6.4) in accordance with the specifications of 8.1.4, the measuring cell (6.2) is immersed, the lid is closed, and the solution is stirred for at least one minute Once a constant temperature of (25 ± 0,1) °C has been reached in the solution, the measured value, σT, is recorded Expression of results -1 Report the electrical conductivity of the sample at 25 °C, expressed in µS cm , rounded to the nearest -1 0,01 µS cm 10 Precision 10.1 General The precision statements have been developed in a round robin study according to EN ISO 4259 [2] NOTE This method has been tested only for ethanol 100 % and ethanol (E85) automotive fuel as a mixture of nominally 85 % (V/V) of ethanol and 15 % (V/V) of gasoline 10.2 Repeatability, r The difference between two test results, obtained by the same operator with the same apparatus under constant operating conditions on identical test material would in the long run, in the normal and correct operation of the test method, exceed the value given in Table in only one case in twenty Licensed copy: The University of Hong Kong, The University of Hong Kong, Version correct as of 30/10/2010 06:04, (c) BSI BS EN 15938:2010 EN 15938:2010 (E) 10.3 Reproducibility, R The difference between two single and independent results, obtained by different operators working in different laboratories on identical test material, would in the long run, in the normal and correct operation of the test method, exceed the value given in Table only in one case in twenty Table — Repeatability and reproducibility Repeatability Reproducibility µS/cm µS/cm r = 0,034 + 0,012 X R = 0,068 + 0,119 X Where X is the mean of the two results being compared 11 Test report The test report shall contain the following information: a) Reference to this European Standard, i.e EN 15938, b) All information required for the complete identification of the sample, c) Sampling procedure applied, d) Result of the test (see 9), i.e the electrical conductivity, σ25, e) Any deviation, by agreement or otherwise, from the procedure specified, f) Date of the test Licensed copy: The University of Hong Kong, The University of Hong Kong, Version correct as of 30/10/2010 06:04, (c) BSI BS EN 15938:2010 EN 15938:2010 (E) Bibliography [1] DIN 51627-4, Automotive fuels — Test methods — Part 4: Determination of electrical conductivity in ethanol fuel [2] EN ISO 4259, Petroleum products — Determination and application of precision 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